Sorry, my brain sticks sometime on an idea and I'm not really Anglophone.

I think the matter with all three scores, and mostly ESB, is that there's not a lot of tracks that have originally been mixed the same way (and I'd bet it's due to the many recording sessions + to notice they played in two studios), then the mixing studios should have considered that in order to respect the characteristic sound of each cue. But no ! I think they wanted too much make it sound the same all the long, trying on the SE to make it sound like new, putting sparkes everywhere !... And even that, they failed to make it.

... And I'm quite happy with that, because imagine if the SE's for instance succeeded in making a sound like we use to hear among the huge sountracks production... You wouldn' care anymore, but what would it have look like? The "pristine" prequels soundtracks ? No thanks ! :)

The prototype for CD1 I just listened makes me think there's not a lot of things like this out there. Despite a few flatness remaining here and there it makes a very rich panorama of the diversity of sounds that may pop up from the same orchestra through many sound takes. Not mentionning the depht from the RSO's cues that can be close to a vinyl as no CD produced nowadays use to show... So, don't have any regrets ! ;)